1. Field of the Invention
The present invention relates to a device for delivering an irrigation liquid for the cultivation of green plants in pots of the type indicated in the preamble of the attached claim 1.
2. Prior Art
In the field of irrigation systems for green plants in pots, a long felt need is that of providing efficient xe2x80x9csub-irrigationxe2x80x9d systems, that is, systems adapted to provide the irrigation liquid to the plant from the bottom.
xe2x80x9cSub-irrigationxe2x80x9d systems of the known type are essentially divided into two different categoriesxe2x80x94each one with different variantsxe2x80x94using a different operating principle.
A first sub-irrigation system of the known type, currently the most widespread, provides for the use of a container for housing the soil, under which a reservoir for storing the irrigation liquid is provided, which is structurally independent from the container. Between the container and the reservoir a space is provided so as to prevent the irrigation liquid from coming into contact with the soil.
In this case, the natural evaporation of water creates a certain humidity in the soil itself, whereas the plants tend to develop root systems that slowly tend to protrude into the lower reservoir and thus into the irrigation liquid.
A first disadvantage of this sub-irrigation system is essentially related to the constant and unavoidable evaporation of the irrigation liquid, which must be added with a certain frequency in the storage reservoir.
On the other hand, another disadvantage is related to the time needed for ensuring the subsistence of the plants, which is only attained when the root system of the plants has sufficiently developed itself so as to reach the irrigation liquid lying below.
A second sub-irrigation system of the known type, described for example in European patent application EP 0 515 207, provides for the use of the microcapillarity of a porous material housed within an elongated hollow element having a first end immersed in a reservoir for storing the irrigation liquid, and a second end which may be either substantially extending perfectly flush with the soil to be irrigated or which may be positioned within the same.
Also in this case, the soil is housed in a container under which the reservoir for storing the irrigation liquid is housed, which is structurally independent from the container itself.
Although this second sub-irrigation system is improved with respect to the previous one, especially in terms of a more correct irrigation of the soil, nevertheless it possesses some drawbacks that have not been overcome yet, and which are essentially related to the following factors:
i) an uneven irrigation of the soil, which is humidified only in a localized way, that is, in the vicinity of the end of the elongated hollow element lying perfectly flush with or positioned in the soil;
ii) an extremely slow feeding rate of the irrigation liquid, which in most cases is not proportional per se to the drying rate of the soil; and
iii) the considerable size of the system as a whole, the soil to be watered being equal; this is due to the presence of the reservoir for storing the irrigation liquid under the container for housing the soil.
Thus, the technical problem underlying the present invention is that of overcoming the drawbacks of the sub-irrigation systems of the prior art, ensuring in particular that the soil is irrigated in optimum conditions for the growth and/or the preservation of the plant.
According to a first aspect of the invention, this problem is solved by a device for delivering an irrigation liquid for the cultivation of plants comprising an elongated element (9) for the capillary upwelling of the irrigation liquid (L) from a first storage zone (A1) of the irrigation liquid (L) to a plant cultivation medium (C), said elongated element (9) being provided with means for putting in liquid communication at least one liquid inlet opening (12, 29) to be positioned in the first storage zone (A1) with at least one liquid outlet opening (13, 38) to be positioned outside of the first storage zone (A1), and a hollow body (14) wherein a second storage zone (A2) of the irrigation liquid (L) is defined and which is intended to be immersedxe2x80x94during usexe2x80x94in the plant cultivation medium (C), said hollow body (14) being provided with at least one liquid-permeable portion (36) and being fastened in a liquid-tight manner to said elongated element (9) around said liquid outlet opening (13, 38).
In the following description and in the subsequent claims, the expression xe2x80x9cplant cultivation mediumxe2x80x9d is used to indicate any suitable material for the germination, the growth and the vegetation of a plant, such as for example soil or material in gel form.
On the other hand, in the following description and in the subsequent claims, the expression xe2x80x9cirrigation liquidxe2x80x9d is used to indicate any suitable liquid adapted to ensure the correct development and the correct vegetative activity of a plant, such as for example water, to which a fertilizer may possibly be added.
Advantageously, the delivering device of the invention allows to accomplish an optimum irrigation of the plant cultivation medium thanks to the provision of a hollow body which, during use, is immersed in the cultivation medium, and in which a second zone for storing the irrigation liquid is defined, such zone being in constant fluid communication with the first storage zone thanks to an elongated element extending between the same.
The hollow body is provided with at least one liquid-permeable portion and, as such, it delivers the irrigation liquid towards the plant cultivation medium, as a function of the humidity of said medium.
In this way, the delivering device of the invention favors the drying of the superficial layer of the plant cultivation medium, so as to ensure a continuous oxygenation of the same, and it irrigates in a natural way only the deepest layers of the plant cultivation medium, so as to obtain an optimum, constant and balanced humidification of the same, always proportional to the liquid requirements of the plant.
Advantageously, the delivering device of the invention also enables to ensure a long duration of the irrigation liquid, which is delivered only to the extent to which the same is actually needed, thus obviating the need of continuous liquid additions into the first storage zone.
Advantageously, the delivering device of the invention may be used both with an ad hoc plant container and with a conventional plant container, provided thatxe2x80x94as it will be better shown hereinafterxe2x80x94suitable measures are taken for defining below the container an airspace adapted to receive the irrigation liquid.
Thus, according to a second aspect thereof, the invention provides, for solving the above-identified technical problem, a plant container, a container assembly and a delivering device.
In a further aspect thereof, finally, the invention provides for solving the above-identified technical problem by a method for delivering an irrigation liquid to a plant cultivation medium.